Mobile radio telecommunication terminals comprising two or more radio interfaces for establishing radio connections according to different radio protocols are known in the art. The radio interfaces, for example, are dedicated for establishing radio connections according to a WLAN (Wireless Local Area Network)—, a 2G (2nd Generation, e.g. GSM, Global System for Mobile Communication)—, 2.5G (2.5 Generation; e. g. GPRS, General Packet Radio Service)—, 3G (3rd Generation; e.g. UMTS, Universal Mobile Telecommunications System) and further generation data transmission protocols. In order to access a certain radio service, the radio interfaces establish a radio connection to an access network comprising various sub-radio access networks according to the various radio protocols. For example, an access network may comprise both WLAN sub-radio access networks and cellular (2.5G or 3G) sub-radio access networks. While the WLAN sub-radio access networks offer a high bandwidth but only a limited local availability, the cellular sub-radio access network provides moderate bandwidth on an almost full-scale local coverage. The sub-radio access networks interoperate with each other in order to make mobility from one sub-radio access network to another possible, providing at least session continuity.
The mobile radio telecommunication terminal comprising multiple radio interfaces is provided with means for selecting one of the radio interfaces for establishing a radio connection for data transmission and reception. Looking at the state of the art, known telecommunication terminals select, by default, the radio interface assigned to a sub-radio access network of the best, preferably global, coverage. In the above example, the telecommunication terminal would connect to the radio interface assigned to the cellular sub-radio access network. Periodically, the telecommunication terminal scans the WLAN environment in order to detect whether the WLAN sub-radio access network is available. When a WLAN sub-radio access network is available, i.e. the available quality of data transmission and reception across the WLAN sub-radio access network is above a certain quality-level, the telecommunication terminal would select the WLAN radio interface and connect to the WLAN sub-radio access network, deselecting the cellular radio interface and leaving the cellular sub-radio access network. When the WLAN sub-radio access network is no longer available, i.e. the available quality of data transmission and reception across the WLAN radio connection falls below a certain quality-level, the telecommunication terminal would change from the WLAN radio interface back to the cellular radio interface.
The known method for establishing a radio connection for transmitting and receiving data across one of a plurality of radio interfaces of a mobile radio telecommunication terminal depends only on the local availability of the sub-radio access networks and does not take into consideration other factors such as the bandwidth available on the radio connections comprising the various radio interfaces or such as the bandwidth desired for a certain radio service. Further, a heavy drawback of the known method is the fact that it is very energy-inefficient, because the telecommunication terminal scans the network environment periodically in order to detect the sub-radio access networks of the network environment.
Therefore, it is an object of the present invention to establish a radio connection for transmitting and receiving data across one of a plurality of radio interfaces of a mobile radio telecommunication terminal more efficiently without waste of energy and waste of bandwidth on the radio connections.